Pyrene compound and organic light emitting diode device including the same

ABSTRACT

A pyrene compound and an organic light emitting diode device including the same are disclosed. The organic light emitting diode device includes at least two stacks provided between a first electrode and a second electrode, and a charge generation layer provided between the stacks and including an N type charge generation layer and a P type charge generation layer, wherein the N type charge generation layer is made of the pyrene compound.

This application claims the benefit of Korean Patent Application No.10-2012-0097357 filed on Sep. 3, 2012, which is incorporated herein byreference for all purposes as if fully set forth herein.

BACKGROUND

1. Field of the Disclosure

This document relates to an organic light emitting diode device, andmore particularly, to an organic light emitting diode device including apyrene compound.

2. Discussion of the Related Art

In recent years, with the development of multi-media, the importance ofa flat panel display (FPD) has increased. To satisfy the demand, variousdisplays such as a liquid crystal display (LCD), a plasma display panel(PDP), a field emission display (FED), and an organic light emittingdiode device have been put to practical use.

Particularly, the organic light emitting diode device is a self-emissivedevice, which represents fast response speed of 1 ms or less and lowpower consumption. Further, since the organic light emitting diodedevice has an excellent viewing angle, the organic light emitting diodedevice is beneficial as a moving picture display medium regardless ofthe size of a device. In addition, since the organic light emittingdiode device may be fabricated at a low temperature and a manufacturingprocess thereof is simple based on an existing semiconductor processtechnique, it is spotlighted as a next-generation flat panel display.

The organic light emitting diode device includes a cathode, an anode andan organic emission layer interposed between the cathode and the anode.An electron provided from the cathode is combined with a hole providedfrom the anode at the emission layer to form an exciton. The exciton istransited into a ground state from an excited state, thereby emittinglight.

The organic light emitting diode device has been developed as variousstructures. Among them, a tandem organic light emitting diode devicemanufacturing by stacking a plurality of emission layers has beendeveloped. The organic light emitting diode device has a plurality ofstack structures including a hole injection layer/hole transportlayer/emission layer/electron transport layer/electron injection layer.Particularly, a charge generation layer including N type and P typecharge generation layers is formed between the stacks, so that a chargeis generated or the charge is injected into each emission layer.

However, in the charge generation layer, an injection characteristic ofan electron generated by charge generation at an interfacial surface ofa hole injection layer adjacent to a P type charge generation layer dueto an energy level difference between an N type charge generation layerand the P type charge generation layer in the N type charge generationlayer is deteriorated. When the N type charge generation layer accordingto the related art is doped with alkaline metal, the alkaline metal isdiffused into the P type charge generation layer so that life span ofthe device is deteriorated.

SUMMARY

A pyrene compound is represented by the following chemical formula 1:

in the chemical formula 1, the A is one selected from C, N, S, and O,the B and R1 are one selected from a hetero aromatic group having 6 to24 carbon atoms which includes or does not include a neighboring A, asubstituted or unsubstituted aromatic arylamine group, or a substitutedor unsubstituted hetero aromatic arylamine group, and the n is aninteger in the range of 1 to 4. In another aspect, there is an organiclight emitting diode device including at least two stacks providedbetween a first electrode and a second electrode and a charge generationlayer provided between the stacks and including an N type chargegeneration layer and a P type charge generation layer, wherein the Ntype charge generation layer is made of the pyrene compound.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention andtogether with the description serve to explain the principles of theinvention. In the drawings:

FIG. 1 is a view illustrating an organic light emitting diode deviceaccording to an exemplary embodiment of the present invention;

FIG. 2 is a graph illustrating a current density according to a drivingvoltage of the organic light emitting diode device fabricated accordingto an exemplary embodiment of the present invention; and

FIG. 3 is a graph showing a life span deterioration ratio according atime of according to the organic light emitting diode device fabricatedaccording to an exemplary embodiment of the present invention.

DETAILED DESCRIPTION

Reference will now be made in detail to embodiments of the invention,examples of which are illustrated in the accompanying drawings. Whereverpossible, the same reference numbers will be used throughout thedrawings to refer to the same or like parts. It will be paid attentionthat detailed description of known arts will be omitted if it isdetermined that the arts can mislead the embodiments of the invention.

FIG. 1 is a view illustrating an organic light emitting diode deviceaccording to an exemplary embodiment of the present invention.Hereinafter, an organic light emitting diode device in which two stacksare laminated is described by way of example, but the present inventionis not limited thereto.

Referring to FIG. 1, the organic light emitting diode device 100according to an exemplary embodiment of the present invention may be awhite organic light emitting diode device having yellow and blue lights.In detail, the organic light emitting diode device 100 includes a firstelectrode 120 on a substrate 110, a first stack 130 disposed on thefirst electrode 120 and including a first emission layer 133, a chargegeneration layer 140 disposed on the first stack 130, a second stack 150disposed on the charge generation layer 140 and including a secondemission layer 153, and a second electrode 160 disposed on the secondstack 150.

The substrate 110 may be made of transparent glass and plastic material,or conductive material. The first electrode 120 is an anode electrodeinjecting a hole and may be a transparent electrode transmitting light.The first electrode 120 is configured by one of Indium Tin Oxide (ITO),Indium Zinc Oxide (IZO), or Zinc Oxide (ZnO). The organic light emittingdiode device 100 may include a protective layer 115 between thesubstrate 100 and the first electrode 120. The protective layer 115reflects light upward and may be made of one aluminum (Al), silver (Ag),and nickel (Ni) at a lower portion of the first electrode 120.

The first stack 130 disposed on the first electrode 120 may include afirst emission layer 133 emitting blue light. The first stack 130 mayinclude only a blue emission layer as the first emission layer 133 andemit blue light to increase color stability of blue. The first emissionlayer 133 is an emission layer emitting blue light, and a fluorescentblue dopant may be mixed with one host. For example, the first emissionlayer 130 may be formed by mixing 1,6-Bis(diphenylamine)pyrene or TBPe(tetrakis(t-butyl)perylene) being a fluorescent blue dopant with a hostmaterial such as AND(9,10-di(2-naphthyl)anthracene) or DPVBi(4,4′-bis(2,2-diphenylethen-1-yl)-diphenyl). The fluorescent blue dopantmay be a deep or sky blue dopant. For example, the deep blue dopant mayinclude 4′-N,N-diphenylaminostyryl-triphenyl (DPA-TP),2,5,2′,5′-tetrastyryl-biphenyl (TSB), or anthracene derivative.

For example, the sky blue dopant may includep-bis(p-N,N-diphenyl-aminostylrl)benzene or phenylcyclopentadiene.

The first stack 130 may further include a first hole injecting layer(HIL) 131 formed between the first electrode 120 and the first emissionlayer 133, and a first electron transport layer (HTL) 134 formed betweenthe first emission layer 133 and the charge generation layer 140.

The first HIL 131 may easily inject a hole from the first electrode 120to the first emission layer 133. The first HIL 131 may be made of atleast one selected from the group consisting of cupper phthalocyanine(CuPc), poly(3,4)-ethylenedioxythiophene (PEDOT), polyaniline (PANI),and N,N-dinaphthyl-N,N′-diphenyl benzidine (NPD), but the presentinvention is not limited thereto.

The first HTL 132 functions to easily transport a hole. The first HTL132 may be made of at least one selected from the group consisting ofN,N-dinaphthyl-N,N′-diphenyl benzidine (NPD),N,N′-bis-(3-methylphenyl)-N,N′-bis-(phenyl)-benzidine (TPD), s-TAD, and(4,4′,4″-Tris(N-3-methylphenyl-N-phenyl-amino)-triphenylamine (MTDATA),but the present invention is not limited thereto.

The first electron transport layer (ETL) 134 functions to easilytransport an electron. The first ETL 134 may be made of at least oneselected from the group consisting of tris(8-hydroxyquinolino)aluminum)(Alq3), PBD, TAZ, Spiro-PBD, BAlq, and SAlq, but the present inventionis not limited thereto.

Meanwhile, a charge generation layer (CGL) 140 disposed on the firststack 130 is a PN junction charge generation layer where a junction isformed between an N type charge generation layer 141 and a P type chargegeneration layer 142. The PN junction CGL 140 generates and injects thecharge to the respective emission layers or separately injects a holeand an electron into each emission layer. That is, the N type CGL 141supplies an electron to the first emission layer 133 adjacent to thefirst electrode 120 and the P type CGL 142 supplies a hole to the secondemission layer 153 adjacent to the second electrode 160, so thatluminous efficiency of the organic light emitting diode device includinga plurality of emission layers may be increased and a driving voltagemay be reduced.

The N type CGL 141 is made of pyrene compound, and a detaileddescription thereof will be described below. The P type CGL 142 may bemade of metal or an organic material doped with a P type dopant. Here,the metal may include one selected from the group consisting of Al, Cu,Fe, Pb, Zn, Au, Pt, W, In, Mo, Ni, and Ti, and an alloy thereof. A Ptype dopant and a host material used in an organic material doped withthe P type dopant may use a generally used material. For example, the Ptype dopant may be one material selected from the group consisting of2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4-TCNQ), aderivative of tetracyanoquinodimethane, iodine, FeCl3, FeF3, and SbCl5.Further, the host may be one material selected from the group consistingof N,N′-D(naphthalene-1-1)-N,N-diphenyl-benzidine (NPB),N,N′-diphenyl-N,N′-bis(3-methyphenyl)-1,1-biphenyl-4,4′-diamine (TPD),and N,N′,N′-tetranaphthyl-benzidine (TNB).

The second stack 150 disposed on the CGL 140 may include the secondemission layer 153 emitting yellow light. The second emission layer 153may include a yellow dopant in a host or red and green dopants in onehost.

For example, when the second emission layer 153 includes the yellowdopant in the host, the second emission layer 153 may use the samematerial as that of the host of the first emission layer 133 as the hostand a blue dopant, and may use Irpq2acac(bis(phenylquinoline) iridiumacetylacetonate). Further, when the second emission layer 153 includesred and green dopants in one host, Ir(piq)₂acac(bis(phenylisoquinoline)iridium acetylacetonate) may be used in the foregoing host as a redphosphoresce dopant. An Irppy3(tris(phenylpyridine) iridium) may be usedas the red phosphoresce dopant.

The second stack 150 may further include a second hole injection layer151 and a second hole transport layer 153 formed between the CGL 140 andthe second emission layer 153, and a second electron transport layer 154and an electron injection layer (EIL) 155. The second hole injectionlayer 151, the second hole transport layer 152, and the second electrontransport layer 154 have the same functions as those of the first holeinjection layer 131, the first hole transport layer 132, and the firstelectron transport layer 134, and thus the description thereof isomitted.

The EIL 155 functions to easily inject an electron, and may useAlq3(tris(8-hydroxyquinolino)aluminum), PBD, TAZ, Spiro-PBD, BAlq, orSAlq, but the present invention is not limited thereto. In addition, theEIL 155 may be made of a metal halide compound. For example, the metalhalide compound may be one selected from the group consisting of MgF2,LiF, NaF, KF, RbF, CsF, FrF, and CaF2, but the present invention is notlimited thereto.

The second electrode (cathode) 160 may be mode of a transparent materialso that light emitted from the emission layers 133 and 135 may beoutputted to a front surface. For example, the second electrode 160 maybe made of one of indium tin oxide (ITO), indium zinc oxide (IZO), andzinc oxide (ZnO).

The N type CGL 141 of the present invention may be made of a pyrenecompound represented as a following chemical formula 1.

In the chemical formula 1, the A is one selected from C, N, S, and O,the B and R1 are one selected from a hetero aromatic group having 6 to24 carbon atoms which includes or does not include a neighboring A, asubstituted or unsubstituted aromatic arylamine group, or a substitutedor unsubstituted hetero aromatic arylamine group, and the n is aninteger in the range of 1 to 4.

The R1 neighboring the B including the A forms or does not form a fusedring.

The chemical formula 1 is represented as following chemical formulas 2to 8.

In the chemical formulas 2 to 8, each substituent may form a fused ringwith a neighboring substituent.

The compound represented as the chemical formula 1 is expressed ascompounds of following P1 to P26.

At least one substituent in the chemical formula 1 is substituted innumbers 1, 3, 6, and 8 locations of a pyrene.

Since number 2 and 6 locations of the pyrene in the chemical formula 1are easily substituted and there is a π interacted carbon in a betalocation from a substituted location, an orbital associated with πinteraction of the carbon may be used in interaction with transitionmetal.

In detail, referring to a following chemical formula 9, when lithium(Li) is doped with an N type dopant, a site having a rich electron ispositioned at a location B, so that the lithium (Li) doped with the Ntype dopant easily interacts with lithium being a system having arelatively deficient electron that enables stronger interaction whileforming the chemically stablest hexagonal ring shape. In this case, alocation A directly donates the electron or functions a linker ofdonating.

Hereinafter, a synthesis example of the pyrene compound used for the Ntype CGL of the present invention and the organic light emitting diodedevice including the same will be described with reference to afollowing synthesis example and embodiment. However, embodiments will bedescribed by way of example only, and the present invention is notlimited to following embodiments.

Synthesis Example 1) Synthesis of 2,4-dibromo-9-phenyl-9H-carbazole (B)

Prepared Example Synthesis of Dibromo Pyrene

A first solution including bromine 16 g and chloroform 100 ml wasdropped in a second solution obtained by solving pyrene 10.0 g (49.4mmol) in chloroform 250 ml while agitating the second solution at atemperature of 23° C. for 7 hours. After additionally agitating thesecond solution for one hour, an obtained reaction liquid (includingcrystal) was filtered so that a crystal was obtained. A dibromo pyrene11.3 g is obtained by washing the crystal and then drying the washedcrystal under reduced pressure (yield 63%) GC-Mass (theoretical value:283.16 g/mol, measured value: 282 g/mol).

2) Manufacture of compound A: synthesis of 1,6-di(quinolin-3-yl)pyrene(A)

Quinoline-3-boronic acid (2.2 g, 12.2 mmol), trioctylmethylammoniumchloride (trademark name: Aliquat336 (hereinafter referred to as

Aliquat336

), prepared by Aldrich Corporation, 0.74 g), palladium acetate (1.3 mg),tris(o-methoxyphenyl)phosphine (13.3 mg), toluene (58 ml), and sodiumcarbonate water solution (17.8 mmol) were added to dibromo pyrene (2.0g, 5.6 mmol) synthesized in the prepared example and they were agitatedat a temperature of 100° C. of four hours. A crystal was obtained bycooling the resultant reaction liquid at room temperature and filteringthe cooled reaction (including the crystal). The compound A of 1.2 g wasobtained by washing the crystal in an order of toluene, water, andmethanol, and drying the washed crystal under reduced pressure (yield46%).

GC-Mass (theoretical value: 456.16 g/mol, measured value: 456 g/mol),1H-NMR (THF-d8, 500 MHz) (ppm) 7.58 (m, 2H), 7.68˜7.74 (m, 8H),8.04˜8.06 (m, 4H), 8.22 (m, 2H), 9.03 (m, 2H)

3) Manufacture of compound B: synthesis of 1,6-di(quinolin-8-yl)pyrene(B)

Quinoline-8-boronic acid (2.2 g, 12.2 mmol), trioctylmethylammoniumchloride (trademark name: Aliquat336 (hereinafter referred to as

Aliquat336

), prepared by Aldrich Corporation, 0.74 g), palladium acetate (1.3 mg),tris(o-methoxyphenyl)phosphine (13.3 mg), toluene (58 ml), and sodiumcarbonate water solution (17.8 mmol) were added to dibromo pyrene (2.0g, 5.6 mmol) synthesized in the prepared example and they were agitatedat a temperature of 100° C. of four hours. A crystal was obtained bycooling the resultant reaction liquid at room temperature and filteringthe cooled reaction (including the crystal). The compound B of 1.8 g wasobtained by washing the crystal in an order of toluene, water, andmethanol, and drying the washed crystal under reduced pressure (yield48%).

GC-Mass (theoretical value: 456.16 g/mol, measured value: 456 g/mol),1H-NMR (THF-d8, 500 MHz) (ppm) 7.49˜7.71 (m, 10H), 7.83 (m, 2H),8.00˜8.06 (m, 6H), 8.81 (m, 2H)

4) Manufacture of compound C: synthesis of1,6-di(1,10-phenanthrolin-5-yl)pyrene (C)

1,10-phenenthrene-5-boronic acid (2.2 g, 12.2 mmol),trioctylmethylammonium chloride (trademark name: Aliquat336 (hereinafterreferred to as

Aliquat336

), prepared by Aldrich Corporation, 0.74 g), palladium acetate (1.3 mg),tris(o-methoxyphenyl)phosphine (13.3 mg), toluene (58 ml), and sodiumcarbonate water solution (17.8 mmol) were added to dibromo pyrene (2.0g, 5.6 mmol) synthesized in the prepared example and they were agitatedat a temperature of 100° C. of four hours. A crystal was obtained bycooling the resultant reaction liquid at room temperature and filteringthe cooled reaction (including the crystal). The compound C of 2.4 g wasobtained by washing the crystal in an order of toluene, water, andmethanol, and drying the washed crystal under reduced pressure (yield77%).

GC-Mass (theoretical value: 558.63 g/mol, measured value: 558 g/mol),1H-NMR (THF-d8, 500 MHz) (ppm) 7.26 (m, 2H), 7.55 (m, 2H), 7.71˜7.77 (m,6H), 8.00˜8.06 (m, 8H), 8.80 (m, 4H)

Comparative Example

Hereinafter, disclosed is an embodiment of fabricating an organic lightemitting diode device using a pyrene compound prepared in the foregoingsynthesis example as an N type CGL.

A layer structure of the embodiment is the same as that of thecomparative example to be described below. The difference is that a hostmaterial of the N type CGL is compounds A, B, C andB-phen(4,7-diphenyl-1,10-phenanthroline). First, a first electrode wasformed on a transparent substrate by indium tin oxide (ITO) being ananode material.N,N′-diphenyl-N,N′-bis-[4-(phenyl-m-tolylamino)-phenyl]-biphenyl-4,4′-diaminehaving a thickness of 10 nm is formed on the first electrode to form ahole injection layer. NPD(4,4′-bis[N-(1-naphthyl)-N-phenylamino]-biphenyl)(N,N′-diphenyl-N-naphthyl-N′-biphenyl-1,1′-biphenyl-4,4″-diamine) havinga thickness of 100 nm was deposited on the hole injection layer to forma hole transport layer. An emission layer having a thickness of 200 Åincluding a fluorescent blue dopant in a fluorescent host materialexpressed in a following exemplary molecule 1 was formed on the holetransport layer. An electron transport layer was formed on the emissionlayer by depositing Alq3 having a thickness of 350 Å, and a CGL wasformed on the electron transport layer. In this case, the CGL is dividedinto two layers which are an N type layer and a P type layer. The N typelayer is formed by co-depositingB-phen(4,7-diphenyl-1,10-phenanthroline) expresses by a followingexemplary molecule 2 and metal dopant lithium with a volume ratio of 1%to 50%. The P type was formed by depositingHAT-CN(dipyrazino[2,3-f:2′,3′-h]quinoxaline-2,3,6,7,10,11-hexacarbonitril)represented as a following exemplary molecule 3 having a thickness of100 Å. Finally, a second electrode as a cathode was formed on the CGL byusing protective metal such as Al.

Example 1

Under the same process conditions as those of the comparative example,an N type CGL is formed using the foregoing prepared compound A insteadof B B-phen(4,7-diphenyl-1,10-phenanthroline) represented as theexemplary molecule 2.

Example 2

Under the same process conditions as those of the comparative example,an N type CGL is formed using the foregoing prepared compound B insteadof B B-phen(4,7-diphenyl-1,10-phenanthroline) represented as theexemplary molecule 2.

Example 3

Under the same process conditions as those of the comparative example,an N type CGL is formed using the foregoing prepared compound C insteadof B B-phen(4,7-diphenyl-1,10-phenanthroline) represented as theexemplary molecule 2.

Driving voltages, current efficiencies, quantum efficiencies, colorcoordinates, and life spans of the organic light emitting diode deviceaccording to the first to third embodiments and the comparative exampleare measured and listed in a following table 1. Further, currentdensities according to driving voltages are measured and illustrated inFIG. 2, and a deterioration rate of luminance according to a time ismeasured and illustrated in FIG. 3.

TABLE 1 Life Driving Current Quantum Color span voltage efficiencyefficiency coordinates (T80, (V) (cd/A) (%) CIE_x CIE_y hr) Example 16.0 6.8 7.4 0.135 0.105 220 Example 2 6.6 6.8 7.6 0.135 0.102 190Example 3 6.3 6.6 7.1 0.135 0.106 80 Comparative 5.9 6.6 7.0 0.134 0.109160 example

As listed in the table 1, it will be appreciated that the organic lightemitting diode device fabricated according the first to thirdembodiments of the present invention can significantly improve quantumefficiency while representing color coordinates of the same level asthat of the comparative example. Particularly, referring to FIG. 2, thecurrent density according to the driving voltage is improved, and a lifespan characteristic is significantly improved as shown in FIG. 3.

Therefore, the pyrene compound and the organic light emitting diodedevice including the same according to the embodiment of the presentinvention can improve the quantum efficiency and the life spancharacteristic as compared with an organic light emitting diode deviceaccording to the related art.

Although embodiments have been described with reference to a number ofillustrative embodiments thereof, it should be understood that numerousother modifications and embodiments can be devised by those skilled inthe art that will fall within the scope of the principles of thisdisclosure. More particularly, various variations and modifications arepossible in the component parts and/or arrangements of the subjectcombination arrangement within the scope of the disclosure, the drawingsand the appended claims. In addition to variations and modifications inthe component parts and/or arrangements, alternative uses will also beapparent to those skilled in the art.

What is claimed is:
 1. A pyrene compound represented by the followingchemical formula 1:

wherein, A is one selected from C, N, S, and O, the B and R₁ is oneselected from a hetero aromatic group having 6 to 24 carbon atoms whichincludes or does not include a neighboring A, a substituted orunsubstituted aromatic arylamine group, or a substituted orunsubstituted hetero aromatic arylamine group, and the n is an integerin the range of 1 to
 4. 2. The pyrene compound of claim 1, wherein R₁neighboring the B including the A forms or does not form a fused ring.3. The pyrene compound of claim 1, wherein chemical formula 1 isrepresented by the following chemical formulas 2 to 8,

and each substituent forms a fused ring with a neighboring substituentin the chemical formulas 2 to
 8. 4. The pyrene compound of claim 1,wherein the compound represented as the chemical formula 1 is expressedas compounds of following P1 to P26.


5. The pyrene compound of claim 1, wherein at least one substituent inthe chemical formula 1 is substituted in numbers 1, 3, 6, and 8locations of a pyrene.
 6. An organic light emitting diode devicecomprising: at least two stacks provided between a first electrode and asecond electrode; and a charge generation layer provided between thestacks and including an N type charge generation layer and a P typecharge generation layer, wherein the N type charge generation layer ismade of the pyrene compound represented by the following chemicalformula 1:

wherein, A is one selected from C, N, S, and O, the B and R₁ is oneselected from a hetero aromatic group having 6 to 24 carbon atoms whichincludes or does not include a neighboring A, a substituted orunsubstituted aromatic arylamine group, or a substituted orunsubstituted hetero aromatic arylamine group, and the n is an integerin the range of 1 to
 4. 7. The organic light emitting diode device ofclaim 6, wherein each of the stacks comprises a hole injection layer anda hole transport layer formed at one side of the stack and an electrontransport layer formed at an opposite side of the stack, while beinginterposed an emission layer therebetween.
 8. The organic light emittingdiode device of claim 6, wherein stacks adjacent to the second electrodeamong the stacks further comprise an electron injection layer.
 9. Theorganic light emitting diode device of claim 6, wherein emission layersof the stacks emit lights of different colors, respectively.
 10. Theorganic light emitting diode device of claim 6, wherein the N typecharge generation layer is doped with alkaline metal.
 11. The organiclight emitting diode device of claim 6, wherein R₁ neighboring the Bincluding the A forms or does not form a fused ring.
 12. The organiclight emitting diode device of claim 6, wherein chemical formula 1 isrepresented by the following chemical formulas 2 to 8,

and each substituent forms a fused ring with a neighboring substituentin the chemical formulas 2 to
 8. 13. The organic light emitting diodedevice of claim 6, wherein the compound represented as the chemicalformula 1 is expressed as compounds of following P1 to P26.


14. The organic light emitting diode device of claim 6, wherein at leastone substituent in the chemical formula 1 is substituted in numbers 1,3, 6, and 8 locations of a pyrene.